Tensile engineering offers superior design flexibility over other building materials. To maximise its potential, it’s helpful to understand how it all works and what to consider during a project.
Tensile fabric structures are lightweight, strong and durable systems. They use tensioned fabric to create outdoor and indoor architectural solutions including shade canopies, walkway covers, retractable roofing systems and art sculptures.
These structures are truly versatile for a host of applications and can span large areas with minimal support. Alongside their functional use, they can diffuse light, dampen acoustics and make a design statement.
They are formed by tensioning fabric across or around an aluminium or steel framework – in a true tensile fabric structure, every part of the fabric is in tension.
To give the structure its 3-dimensional stability, the fabric must curve equally in opposite directions. We create a ‘double curvature’ (also known as ‘anticlastic form’ or ‘hyperbolic paraboloid’) into the form of the structure by patterning fabric panels, bonding them into a 3-dimensional shape and then placing them under tension for rigidity. This allows it to deal with any wind and snow loads applied.
Flat panels placed under tension will stretch over time and become unstable if caught by the wind, potentially coming away from fixings. Although we can manufacture flat structures, they require much stronger steel support structures.
Tension is the force used to pull the structure of a material apart. It is the most efficient way of using any material because it utilises the whole cross section at maximum efficiency. For example, a stick will break under compression or bending, long before it would be pulled apart by tension. Tension loads maximise the load capacity of material while requiring the least material.
‘Shape’ and ‘use’ go hand in hand with tensile fabric structure design.
For the greatest structural stability, a tensile fabric shape needs anticlastic curvature (usually expressed as a barrel vault, cone or hyperbolic paraboloid), which creates its distinctive organic form. The more symmetrical the shape, the lighter the steelwork and smaller the foundations.
Triangular tensioned shapes are also very popular as solar shades in hot countries.
Many of our pre-engineered Signature Structures can be modified to provide a cost-effective solution with quick delivery and installation.
These are often more substantial than expected and require large concrete blocks. Tensile structures are effectively large sails capable of pulling a ship from one side of the Atlantic to the other – we prefer our tensile fabric structures to stay very firmly tethered to dry land!
Tensile structures usually need to fix directly into a building’s frame, rather than simply into masonry, so when fixing to an existing building, it’s important to know whether the connections can be made at points where the imparted loads can be managed effectively.
Understanding location is an important part of the design process. For example, the expected wind and snow loads, distance from the coast, altitude above sea level and whether the environment is urban or rural will all affect the design and steelwork finish needed to create a long-lasting tensile fabric structure.
The main considerations with fabric are fire rating, light transmission/reflectivity/absorption, life expectancy, colour, flexibility (for ease of installing larger canopies) and cost. Vast choice in tensile fabric material is available and we’ll always find one to meet your specification requirements. Our Materials page summarises the fabrics and their properties.
A well-designed, engineered and maintained tensile fabric solution is a very cost-effective option over time – comparative with polycarbonate structures and cheaper than glazed structures.
In relation to the area it covers, tensile fabric is an environmentally friendly option. Most architectural-grade fabrics can be recycled, and some are made from highly sustainable materials, such as silicone-coated woven glass fabrics which are produced wholly from silicone.
The curving shapes of tensile canopies mean that rainwater can usually be made to run off at pre-determined points. From there, it can be channelled through the structure’s framework for connection to site drainage or for harvesting, or left to free-drain.
To install tensile structures, we often need to lift single pieces of fabric thousands of square feet in size, or pieces of steel that are hundreds of pounds in weight. This requires large and heavy access equipment, so scheduling is at the top of the list for a seamless installation.
Cleaning tensile fabrics preserves their long-term integrity – this should happen every 12 months with warm soapy water. It’s important to design access for this maintenance into the structure. We can include lugs for harness connections to enable appropriately qualified riggers to walk safely on the canopies, which can easily support the weight of several people.
If your tensile fabric structure requires an inspection, report or maintenance work, we can support you with this. Just request a maintenance quote.
FABRIC ARCHITECTURE SOLUTIONS
UNIT 2, BENFORD COURT
LOWER CAPE, WARWICK
CV34 5DA
+44 (0)1452 612 800
INFO@FABARC.CO.UK
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